Resins containing ionic or ionizable groups with small domain sizes and improved conductivity

ABSTRACT

A polymer or blend is described which contains at least one acrylic resin or vinyl resin having at least one ionic or ionizable group, and at least one additional polymer. The polymer has small domain sizes with respect to the acrylic resin or vinyl resin. The polymer preferably has improved conductivity when formed into a film. Preferably, the polymers are useful in a variety of applications including in the formation of a membrane which is useful in batteries and fuel cells and the like. Methods of making the polymer blends are also described.

This application claims priority under 35 U.S.C. § 119(e) of prior U.S.Provisional Patent Application No. 60/491,005 filed Jul. 30, 2003, whichis incorporated in its entirety by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to polymeric resins, for instance and morespecifically to fluoropolymer and non-perfluorinated polymeric resinscontaining ionic and/or ionizable groups (also referred to as a“polyelectrolyte”), which are useful in a variety of products such aspolyelectrolyte membranes and other thermoplastic articles. The presentinvention further relates to methods of making these resins as well asusing these resins.

Perfluorocarbon ionic exchange membranes provide high cation transport,and have been extensively used as ionic exchange membranes. Polymericion exchange membranes can be referred to as solid polymer electrolytesor polymer exchange membranes (PEM). Because of the severe requirementsfor fuel cell applications, the most commonly used membranes, andcommercially available, are made from perfluorosulfonated Nafion®,Flemion® and Aciplex® polymers. However, reports and literature describethese membranes as working well but show several limitations thatprevent developing the technology further to commmiercialization.Additionally, they work better with gaseous fuels than with liquid fuelswhich may be mainly due to liquid fuel crossover that diminishes cellperformance. A membrane's chemical resistance and mechanical strengthare important properties for fuel cell applications. Indeed, themembrane is often subjected to high differential pressure,hydration-dehydration cycles, as well as other stressful conditions.Also, mechanical strength becomes important when the membrane is verythin such as less than 50 microns. Further, when used with fuel cells orbattery applications, the membrane sits in a very acidic medium attemperatures that can reach 200° C., in an oxidizing and/or reducingenvironment due to the presence of metal ions and sometimes the presenceof solvents. This environment requires that the membrane be chemicallyand electrochemically resistant, as well as thermally stable.

Currently, many fluorine-containing membranes can suffer from one ormore of the following short comings:

-   -   i) high liquid and gas crossover through the membrane;    -   ii) heterogeneous blending between the fluorinated polymer and        other polymers that leads to inferior properties;    -   iii) insufficient chemical resistance in the presence of some        liquid fuels;    -   iv) poor electrochemical resistance;    -   v) lack of heterogeneous distribution of sulfonated groups;    -   vi) poor mechanical properties; and/or    -   vii) poor thermal stability.

U.S. Pat. No. 4,295,952 to de Nora et al. relates to cationic membraneswhich have partly sulfonated tripolymers of styrene, divinylbenzene, andat least one of 2-vinylpyridine, 4-vinylpyridine, and/or acrylic acid.

U.S. Pat. No. 5,679,482 to Ehrenberg et al. relates to fuel cellsincorporating an ion-conducting membrane having ionic groups. Thepolymer forming the membrane contains styrene which has been sulfonatedusing a sulfonation agent. The sulfonation can take place with themonomer or polymer.

U.S. Pat. No. 5,795,668 describes a fuel cell containing a MEA with areinforced polymeric ion exchange membrane (PEM) using Nafion® typepolymers. The PEM is based on a fluorinated porous support layer and areinforced ion exchange membrane with an equivalent weight of about 500to 2000 and a preferred ion exchange capacity of from 0.5 to 2 meq/g dryresin. The porous support layer is made of certain PTFE and PTFEcopolymers. The membrane is a perfluorinated polymer with side chainscontaining —CF₂CF₂SO₃H. It is known from the literature that Nafion(&type polymers can have mechanical failure in methanol fuel cells as wellas problems with liquid crossover.

WO 97/41168 to Rusch relates to a multi-layered ion-exchange compositemembrane having ionic exchange resins, such as fluorinated ornon-fluorinated polystyrene based sulfonates and sulfonatedpolytetrafluoroethylenes.

WO 98/20573 A1 describes a fuel cell containing a highly fluorinatedlithium ion exchange polymer electrolyte membrane (PEM). The PEM isbased on an ion exchange membrane which is imbibed with an aproticsolvent.

WO 98/22989 describes a polymeric membrane containing polystyrenesulfonic acid and poly(vinylidene fluoride), which provides reducedmethanol crossover in direct methanol fuel cell (DMFC) use. However, thepolymer blending process described does not provide an acceptable blendand the sulfonation steps are complicated.

J Holmberg et al., (J. Material Chem. 1996, 6(8), 1309) describes thepreparation of proton conducting membranes by irradiation grafting ofstyrene onto PVDF films, followed by sulfonation with chlorosulfonicacid. In the present invention, a sulfonation step is not required sincethe sulfonated group can be incorporated using a sulfonated monomer.

U.S. Pat. No. 6,252,000 relates to a blend of fluorinated ionexchange/non-functional polymers. Specific examples includeperfluorinated sulfonyl fluoridepolymer/poly(CTFE-co-perfluorodioxolane) blends.

WO 99/67304 relates to an aromatic perfluorinated ionomer prepared bythe copolymerization of sulfonated aromatic perfluorinated monomer withacrylic monomers. The sulfonated group that is present is in thefluorinated aromatic chain of the polymer.

U.S. Pat. No. 6,025,092 relates to a perfluorinated ionomer wherein aVDF monomer is polymerized with a sulfonated monomer.

Moore et al., (J. Membrane Sci., 1992, 75, 7) describes a procedure forpreparing a melt-processable form of perfluorosulfonate ionomersutilizing bulky tetrabutyl ammonium counterions as internal plasticizersto yield the desired melt-flow properties.

Boucher-Sharma et al., (J. Appl. Polym. Sci., 1999, 74, 47), describesthe application of pervaporation of aqueous butenol solutions using athin film composite composed of PVDF coated with a sulfonatedpoly(2,6-dimethyl-1,4-phenylene oxide) polymer. The polymer is then ionexchanged with quaternary ammonium cations having aliphatic substituentsof varying chain lengths.

U.S. Pat. No. 6,011,074 relates to use of quaternary ammonium cations toenhance the ion-exchange properties of perfluorosulfonated ionomers.

Berezina et al. (Russian J. Electrochemistry, 2002, 38(8), 903),describes the effect of tetraalkyl ammonium salts on the transport andstructural parameters of perfloronated membranes including Nafion®-117and MF-4SK. They observe that specific adsorption of organic ions makesthe water clusters of the polymers disintegrate and the elasticity ofside segments diminish thereby significantly decreasing the protonconductivity of the polymer films.

Pastemac et al., (J. Polym. Sci., A: Polym. Chem., 1991, 29(6), 915)relates to the application of pervaporative membranes for C₂-C₄ alkanes,and demonstrates that when Nafion®-117 is treated with tetraalkylammonium bromides, the separation factor increases with increasingcounterion organic chain length.

Smith et al. in European Patent No. 143,605 A2 describes a process wherethe membrane is cation exchanged with tetraalkyl ammonium ions andexpanded by dry stretching to yield a membrane useful for electrolysis.

Feldheim et al., (J. Polym. Sci., B: Polym. Physics, 1993, 31(8), 953)shows a strong dependence of Nafion® thermal stability on the nature ofthe counterion. Metal salts and alkyl ammonium salts were studied. Thethermal stability of the membrane is shown to improve as the size of thecounterion decreases. This inverse relationship of thermal stabilitywith counterion size is attributed to an initial decomposition reactionwhich is strongly influenced by the strength of the sulfonate-counterioninteraction.

The neutralization of Nafion® by tetrabutyl ammonium hydroxide wasfurther studied in various publications by Moore et al. See, forexample, Polymer Chemistry, 1992, 31(1), 1212; Polymer Chemistry, 1995,36(2), 374, J. Polym. Sci. B: Polym. Physics, 1995, 33(7), 1065, andMacromolecules, 2000, 33, 6031.

Furthermore, sulfonated acrylic or sulfonated vinylic polymers aredescribed for use in superabsorbents, diapers, and contact lenses, forinstance. (See J. Mater. Chem., 1996, 6(a), 1309 and Ionics, 1997, 3,214.) However, such type of products has not been described forapplication as membranes for polyelectrolyte membranes and the like.All. patents, publications, and applications mentioned above andthroughout this application are incorporated by reference in theirentirety and form a part of the present application.

Thus, there is a need to overcome one or more of these limits and todevelop a membrane that can be used for applications in liquid fuelcells. More particularly, there is a need to develop a polyelectrolyteto make membranes directly from aqueous or non-aqueous dispersions orsolutions. Also, there is a need to provide compositions and methods ofsynthesis as well as methods of using water or non-aqueous dispersionsof polyelectrolyte having sulfonated or other functionalities. Further,there is a need to provide a method that is easier and environmentallyfriendly. In addition, those skilled in the art would prefer apolyelectrolyte membrane having a higher chemical resistance andmechanical strength.

SUMMARY OF THE INVENTION

Accordingly, a feature of the present invention is to providepolyelectrolytes with higher conductivities.

A further feature is to provide polyelectrolytes wherein the acrylicand/or vinyl resin is uniformly distributed in a second polymer, such asfluoropolymer, such that the clusters or domains are very small andpreferably hardly detectable.

Another feature of the present invention is to provide polyelectrolyteshaving ionic functionalities.

An additional feature of the present invention is to provide apolyelectrolyte membrane having high chemical resistance and/ormechanical strength.

Another feature of the present invention is to provide polymers that canbe formed as a component in polyelectrolyte membranes that avoid one ormore of the shortcomings described above, such as avoiding a high liquidcrossover through the membrane.

A further feature of the present invention is to provide membranes thatcan be made directly from a dispersion or solution of a polymer.

Another feature of the present invention is to provide polyelectrolytewithout separate sulfonation steps.

An additional feature of the present invention is to provide apolyelectrolyte membrane as well as the fuel cell using the membranewhich preferably has reduced fuel crossover and/or reduced arealresistance.

A further feature of the present invention is to provide a membranewhich has a reduced thickness and yet achieves improved reduced fuelcrossover and/or reduced areal resistance.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein, thepresent invention relates to a polymer or polymer blend containing atleast one acrylic resin and/or vinyl resin, wherein the acrylic and/orvinyl resin has at least one ionic or ionizable group, such as asulfonated group. The domain size of the acrylic resin and/or vinylresin in the polymer or polymer blend is preferably 500 nm or less. Thepolymer preferably has an equivalent weight (EW) of from about 200 toabout 8,000.

The present invention further relates to a polymer or polymer blendcontaining at least one acrylic resin and/or vinyl resin, wherein theacrylic and/or vinyl resin has at least one ionic or ionizable group.The polymer or polymer blend when formed into a film preferably has aconductivity of 20 mS/cm or greater, and more preferably a conductivityof 50 mS/cm or greater, such as from about 50 mS/cm to about 200 mS/cm.

The present invention also relates to a method of controlling thepolyelectrolyte phase nodule size in the fluoropolymer matrix, and/orthe proton conductivity of the membrane through, in part, the use of anammonium salt in preparing the polyelectrolyte. The amount and type ofthe ammonium salt can affect the morphology of the polyelectrolytemembrane and its homogeneity.

The present invention also relates to a composition that includes thepolymer product of blending: a) at least one polymer having acrylicand/or vinyl units and at least one ionic or ionizable group; and b) atleast one additional polymer, wherein a) and b) are different. Theadditional polymer can be any compatible polymer, such as athermoplastic polymer (e.g., a thermoplastic non-perfluoropolymer orfluoropolymer). The domain size of the acrylic resin and/or vinyl resinin the polymer or polymer blend is preferably about 500 nm or less.Also, or in the alternative, the composition, when formed into a film,has a conductivity of 20 mS/cm or greater.

The present invention further relates to a composition comprising thepolymer product of a) at least one polymerizable acrylic and/or vinylcontaining monomer(s) and at least one monomer comprising at least oneionic or ionizable group, or both; in the presence of a dispersingmedium. The polymer preferably has an EW of from about 200 to about8,000, and preferably from about 900 to about 1,400. The domain size ofthe acrylic resin and/or vinyl resin in the polymer or polymer blend ispreferably 500 nm or less. Also, or in the alternative, the composition,when formed into a film, has a conductivity of 20 mS/cm or greater.

Also, the present invention relates to a preferred method of making theabove-described compositions, involving conducting a polymerization ofat least one polymerizable acrylic and/or vinyl containing monomer andat least one monomer containing at least one ionic or ionizable group ina dispersing medium. The process includes contacting the acrylic and/orvinyl containing polymer with an ammonium compound or phosphoniumcompound to form ammonium or phosphonium counterions to the ionic orionizable group. The process can further include blending the polymerhaving acrylic and/or vinyl units and at least one ionic or ionizablegroup with at least one additional polymer, preferably a fluoropolymer.The treatment with the ammonium compound (e.g., ammonium salt) or thephosphonium compound (e.g., phosphonium salt) can occur prior toblending, during blending, and/or after blending with the additionalpolymer. After the blending, treatment with the ammonium or phosphoniumcompound, and formation of the film or membrane, the ammonium orphosphonium counterions can then be removed from the ionic or ionizablegroup. The membrane can then be subjected to cross-linking in order tocrosslink the polymer having acrylic and/or vinyl units and at least oneionic or ionizable group with the additional polymer to anycross-linking degree. The cross-linking, if used, is preferably donebefore removal of the ammonium or phosphonium counterions.

Also, the present invention relates to a polymer or polymer blendcontaining at least one acrylic resin and/or vinyl resin, wherein theacrylic and/or vinyl resin has at least one ionic or ionizable grouphaving at least one ammonium and/or phosphonium counterion, such as analkyl ammonium or alkyl phosphonium counterion. Preferably, at least oneadditional polymer, such as a fluoropolymer or non-fluoropolymer, areadditionally present to form the blend.

The present invention also relates to a composition that includes thepolymer product of blending at least one polymer having acrylic and/orvinyl units and at least one ionic or ionizable group having at leastone ammonium counterion or phosphonium counterion, such as an alkylammonium counterion and b) at least one additional polymer, wherein a)and b) are different.

Furthermore, the present invention relates to a polyelectrolyte membranethat includes at least one acrylic and/or vinyl resin or both having atleast one ionic or ionizable group, and at least one additional polymer.The ionic or ionizable group is preferably present in an amount of fromabout 200 to about 2,500 EW. Furthermore, the polyelectrolyte membranepreferably has a methanol crossover rate of 5×10⁻¹⁶ mol/cm²/s or lowerand/or has a areal resistance of 0.3Ωcm² or lower. Furthermore, thethickness of the polyelectrolyte membrane can be about 10 mils or lessand more preferably from about 0.5 to about 5 mils.

The present invention further relates to a polyelectrolyte membranecontaining the polymers or compositions of the present invention andalso relates to a fuel cell, battery, or other devices containing themembrane of the present invention.

In addition, the present invention relates to a membrane electrodeassembly including the above-mentioned membrane, and relates to a fuelcell using this membrane electrode assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a SEM photo of a polymer blend of an acrylic resin or vinylresin having at least one ionic or ionizable group and at least onethermoplastic fluoropolymer. This polymer blend was made using previoustechniques and shows domain sizes which are over 1,000 nm.

FIG. 2 is a SEM photo of a polymer blend of the present invention whichshows domain sizes below 500 nm and shows domain sizes which are barelydetectable.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Perfluorinated polyelectrolyte membranes are used to provide high cationtransport, and have been extensively used as ion exchange membranes.Polymeric ion exchange membranes are referred to as solid polymerelectrolytes or polymer exchange membrane (PEM).

The most commonly used membrane, and commercially available, areNafion®V and Aciplex®. However, there are very few non-perfluorinatedpolyelectrolyte membranes described in the literature. This is due tothe fact that the membrane's chemical resistance, electrochemicalresistance and mechanical strength are important properties for a fuelcell application. Indeed, the membrane is often subject to highdifferential pressure. In addition, mechanical strength becomesimportant when the membrane is very thin (less than 50 microns). Whenused for fuel cell or battery application, the membrane sits in a veryacidic medium at temperatures that could reach 200° C., and in thepresence of metal ions, solvents, and the like, thus requiring highchemical resistance as well as electrochemical resistance. Thoserequirements are often met when a fluorinated base is used becausefluorinated materials have inherent chemical and electrochemicalresistance. However, these membranes show limitations including but notlimited to poor mechanical properties at elevated temperatures (70-200 °C. range), crossover, and mechanical failure after repeatedhydration-dehydration cycling. Additionally, preparing thoseperfluorinated polyelectrolytes requires several steps and involveschemistry that induces a high cost. Developing a chemistry that is easyand cheap will further alleviate commercialization barriers for fuelcells.

The present invention is an improvement over the invention described inU.S. patent application Publication No. US 2003/0064267 A1 whichdescribes a polymer blend containing at least one acrylic resin or vinylresin having at least one ionic or ionizable group and at least onethermoplastic fluoropolymer. Furthermore, the present invention is animprovement over U.S. patent application Ser. No. 10/383,026, filed Mar.6, 2003, which describes a polymer blend containing at least one acrylicresin or vinyl resin having at least one ionic or ionizable group and atleast one non-perfluoropolymer which can include partial fluorination orno fluorination at all. Both of these applications are incorporated intheir entirety by reference herein and form a part of the presentapplication. While these inventions as described in these twoapplications are quite beneficial and have advanced the state of theart, there is always a desire in the industry to provide a more intimateblend such that the domain sizes of the various polymers (e.g., thedomain sizes of the acrylic resin or vinyl resin) are quite small suchthat they are practically not detectable. As shown in FIG. 1, which is aSEM photo of a polymer blend having at least one acrylic resin or vinylresin having at least one ionic or ionizable group and a thermoplasticfluoropolymer, domain sizes are quite visual under magnification. Thedomain sizes at times can be over 1,000 nm. In an effort to improve thistechnology, the present invention provides a polymer blend which is farmore intimate wherein domain sizes of the acrylic resin or vinyl resinpresent in the polymer blend are below 1,000 nm, such as below 500 nmand preferably below 100 nm, and even more preferably below 50 nm insize. As shown in FIG. 2 of the present application, using thetechnology of the present invention, the domain sizes are practicallynot detectable and provide a significant improvement in this technology.In addition, the conductivity of a film formed using the polymer blendsof the present invention is significantly improved as will be discussedin more detail below.

The present invention relates to a polyelectrolyte which contains atleast one acrylic and/or vinyl resin or polymer which bears at least oneionic or ionizable group, such as a sulfonated and/or phosphonatedgroup. As part of the present invention, at least one additional polymercan be present with the acrylic and/or vinyl resin to form a polymerblend. This additional polymer can be a fluoropolymer (perfluoro ornon-perfluoro) or a non-fluoropolymer. Preferably, the additionalpolymer is at least one thermoplastic fluoropolymer. In anotherembodiment, the polymer or blend thereof does not contain anyperfluoropolymer or as an option no fluoropolymers. In one embodiment,the polyelectrolyte is non-perfluorinated and can be present with noother polymers (i.e., it is not present as a blend, or put another way,the non-perfluorinated polyelectrolyte is used alone). In anotherembodiment, the polyelectrolyte is non-perfluorinated and is presentwith one or more other polymers, for instance, as a blend, such as withthermoplastic non-perfluoropolymers. By perfluoro, it is to beunderstood that all hydrogens that are attached to carbon atoms arecompletely replaced with fluorine. As an option, in the presentinvention, some of the hydrogens can be replaced with fluorine or all ofthem. Thus, partial fluorination is possible or no fluorination at all.

The present invention also relates to the resulting product fromblending a) a polyelectrolyte having acrylic or vinyl units or both andat least one ionic or ionizable group and b) at least one additionalpolymer wherein a) and b) are different from one another.

The present invention further relates to a composition comprising thepolymer product of at least one polymerizable vinyl and/or acryliccontaining monomer and at least one monomer comprising at least oneionic or ionizable group or both, wherein the polymerization preferablyoccurs in the presence of an aqueous dispersion.

In the above-identified embodiments, as well as any embodiment herein,the domain size of the acrylic resin and/or vinyl resin or polymer inthe polymer or polymer blend is preferably about 500 nm or less, morepreferably about 100 nm or less or about 75 nm or less, even morepreferably about 50 nm or less. The domain sizes discussed herein arewith respect to maximum domain sizes and/or average domain sizes. In apreferred embodiment, the domain sizes recited are the maximum domainsizes, but can be the average domain sizes. Other suitable domain sizeranges include, but are not limited to, from about 1 nm to about 500 nm,from about 1 nm to about 100 nm, from about 1 nm to about 75 nm, fromabout 1 nm to about 50 nm, from about 10 nm to about 100 nm, from about10 nm to about 75 nm, or from about 10 nm to about 50 nm, or from about1 nm to about 25 nm, or any values or ranges in between these varioussizes. Again, these domain sizes are with respect to maximum domainsizes and/or average domain sizes. These domain sizes are preferably thecase where the blend is formed into a film, layer, or membrane. Also, orin the alternative, the polymer or polymer blends of the presentinvention when formed into a film or membrane preferably have aconductivity of 20 mS/cm or greater, more preferably 50 mS/cm orgreater, even more preferably 75 mS/cm or greater, or 100 mS/cm orgreater, or from about 20 mS/cm to about 300 mS/cm. Other conductivityranges include, but are not limited to, from about 50 mS/cm to about 200mS/cm, from about 75 mS/cm to about 200 mS/cm, from about 80 mS/cm toabout 180 mS/cm, from about 90 mS/cm to about 175 mS/cm, from about 100mS/cm to about 180 mS/cm and any values or ranges in between thesevarious amounts. As stated, the polymer or polymer blends of the presentinvention can have these desirable conductivities alone or incombination with the domain sizes described herein. Preferably, thepolymer or polymer blends of the present invention have both thepreferred domain sizes and conductivities described herein.

The polymer blend of the present invention can be any type of mixture ofthe two polymers described above and throughout this application.Preferably, the polymer blend is an intimate blend of the two polymers.For instance, the polymer blend can be a polymer blend wherein one ofthe polymers at least partially coats onto the other polymer.Preferably, in emulsion or suspension polymerization, the fluoropolymeris coated by the acrylic or vinyl resin or the polymer formed from atleast one polymerized vinyl or acrylic containing monomer and at leastone monomer comprising at least one ionic or ionizable group or both isthe shell. As stated earlier, the acrylic or vinyl resin can partiallycoat or fully coat the fluoropolymer in the preferred embodiment.Preferably, the attachment between the acrylic resin and thefluoropolymer is a physical attachment though attachments other thanphysical attachments are within the bounds of the present inventionincluding chemical attachments. In the preferred embodiment, theparticle typically has a particle size of from about 90 to about 500 nm,and more preferably from about 50 to about 300 nm. The amount offluoropolymer can be from about 5 to about 95 weight % and the amount ofthe acrylic or vinyl resin can be from about 95 to about 5 weight %.Preferably, the fluoropolymer is present in an amount of from about 40%to about 80 weight % and the amount of acrylic or vinyl resin is fromabout 20 to about 60 weight %.

With respect to the fluoropolymer, this fluoropolymer can be ahomopolymer or other type of polymer, and can be a mixture offluoropolymers or a mixture of fluoropolymer with a non-fluoropolymer.Preferably, a thermoplastic fluoropolymer is used. Preferably, thisfluoropolymer or mixtures of fluoropolymers can be any fluoropolymer(s)which can form a polymer blend with the other components, includingother polymers present. Preferably, the fluoropolymer is apoly(vinylidene fluoride) polymer such as a poly(vinylidene fluoride)homopolymer. Other examples of fluoropolymers include, but are notlimited to, a poly(alkylene) containing at least one fluorine atom, suchas polyhexafluoropropylene, polytetrafluoroethylene, poly(vinylfluoride), or combinations thereof. More preferably, the fluoropolymeris a polymeric composition containing from about 30% to about 100 weight% of vinylidene fluoride and from 0% to about 70 weight % of at leastone poly(alkylene) containing at least one fluorine atom, such as,hexafluoropropylene, tetrafluoroethylene, trifluoroethylene (VF3),chlorotrifluoroethylene, and/or vinyl fluoride. Preferably, themolecular weight of the fluoropolymer which can include homopolymers,copolymers, terpolymers, oligomers, and other types of polymers is fromabout 80,000 MW to about 1,000,000 MW and, more preferably from about100,000 MW to about 500,000 MW. The fluoropolymers can be prepared usingthe techniques described in U.S. Pat. Nos. 3,051,677; 3,178,399;3,475,396; 3,857,827; and 5,093,427, all incorporated herein in theirentirety by reference.

With respect to the acrylic resin or polymer, this polymer or resinpreferably contains or bears one or more ionic or ionizable groups.Examples of acrylic resins include polymers (including copolymers,terpolymers, oligomers, and the like) of acrylic acids, methacrylicacids, esters of these acids, or acrylonitrile. The acrylic resin canalso contain other repeating units as well as combinations of differentacrylic acid alkyl esters, methacrylic acid alkyl esters, acrylic acids,methacrylic acids, and acrylonitriles. For purposes of the presentinvention, the acrylic resin can include other polymerized monomers orcan be a mixture of two or more different acrylic resins or canadditionally include non-acrylic resins, such as vinyl monomers andstyrenic monomers.

Examples of vinyl monomers that can be used in the polyelectrolyteinclude, but are not limited to, styrene, vinyl acetate, vinyl ethers,vinyl esters such as VeoVa 9 and VeoVa 10 from Shell, vinyl propionate,vinyl pivalate, vinyl benzoate, vinyl stearate, and the like, and anycombinations thereof. Preferably, the at least one vinyl monomer orresin does not include an aromatic group. In other words, preferably,the vinyl monomer, resin or polymer is a non-aromatic vinyl resin. Thus,the vinyl resin preferably does not include styrene.

Furthermore, the polyelectrolyte contains at least one ionic (e.g.,sulfonate or phosphonate) or ionizable group such as a sulfonated orphosphonated group or sulfonyl groups. An ionizable group is a groupcapable of forming an ionic group, such as cyclic amino acids, sultones,maleic anhydride, mercaptans, sulfides, phosphalanes, and the like.These groups can be part of the polyelectrolyte by any means such asblending an acrylic and/or vinylic resin in the presence of one or moremonomers containing an ionic or ionizable group. In the alternative, oneor more of the monomers used to form the polyelectrolyte can contain theionic or ionizable group. For purposes of the present invention, theionic or ionizable group is not the acid portion of acrylic acid or avinyl resin if used. The ionic or ionizable group is a group in additionto any acrylic acid that may be present especially from the acrylicresin or polymer described above.

Besides the components mentioned above with respect to the acrylicand/or vinylic resin, the acrylic and/or vinylic resin can furthercontain or be formed in the additional presence of one or moreadditional monomers optionally with any type of functional group as longas these monomers are compatible with the overall formation of theacrylic and/or vinylic resin.

As stated earlier, preferably the acrylic and/or vinylic resin is theresult of the polymerization of several monomers, one of which containsthe ionic or ionizable group, and the other which contains the acrylicand/or vinylic units of the acrylic and/or vinylic resin. Morepreferably, the acrylic and/or vinylic resin is formed from polymerizing(1) acrylic acid alkyl esters, (2) methacrylic acid alkyl esters, (3)one or more co-polymerizable monomers which are different from (1) and(2), (4) one or more monomers having at least one functional group, (5)a monomer containing ionic or ionizable groups, such as a sulfonated orphosphonated monomer.

Examples of the acrylic acid alkyl ester (1) include, for example, ethylacrylate, methyl acrylate, butyl acrylate, propyl acrylate, isobutylacrylate, amyl acrylate, 2-ethylhexyl acrylate, hexyl acrylate,fluoroalkyl acrylates, and combinations thereof.

Examples of the copolymerizable monomers (3) include, for example,conjugated dienes (e.g., 1,3-butadiene, isoprene), aromatic alkenylcompounds (e.g., styrene, amethylstyrene, styrene halides), divinylhydrocarbon compounds (e.g., divinyl benzene), and combinations thereof.

Examples of the methacrylic acid alkyl ester (2) include, for example,ethyl methacrylate, methyl methacrylate, butyl methacrylate, propylmethacrylate, isobutyl methacrylate, amyl methacrylate, 2-ethylhexylmethacrylate, hexyl methacrylate, fluoroalkylmethacrylate, andcombinations thereof.

Examples of the functional monomer (4) include, but are not limited to,α, β unsaturated carboxylic acids (e.g., acrylic acid, methacrylic acid,fumaric acid, crotonic acid, itaconic acid); vinyl ester compounds,amide compounds (e.g., acrylamide, methacrylamide,N-methylmethacrylamide, N-methylolmethacrylamide, N-alkylacrylamide,N-alkylacryl methamide, N-dialkyl methacrylamide, N-dialkyl acrylamide);monomers containing hydroxyl group (e.g., hydroxyethyl methacrylate,hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxypropylmethacrylate, diethylene glycol ethyl ether acrylate); monomerscontaining epoxy groups (e.g., glycidyl acrylate, glycidylmethacrylate), monomers containing silanols (e.g., γtrimethoxysilanemethacrylate, γtriethoxysilane methacrylate); monomer containingaldehydes (e.g., acrolein), alkenyl cyanides (e.g., acrylonitrile,methacrylonitrile). The monomers included in (4) can be capable ofcrosslinking. Examples of copolymerizable monomers capable ofcrosslinking include isobutyl methacrylamide, glycidyl methacrylate,diethylene glycol dimethacrylate, and trimethyloxysilane methacrylate.Crosslinking might be desirable for improved mechanical properties andsolvent resistance.

For some specific applications, low molecular weight copolymerizablepolymers or oligomers can be used. Moreover, when a mixture of acrylicacid alkyl ester (1) and methacrylic acid alkyl ester (2) is used, theirratio could be suitably adjusted to achieve the desired properties.

Examples of the monomer containing at least one ionic or ionizable group(5) include, but are not limited to, acrylamid propyl sulfonate, vinylphosphonic acid, vinyl sulfonic acid, sulfopropyl methacrylate,sulfoethyl methacrylate. These monomers can preferably be used either intheir acid form or as a salt derivative. For example, in a seededemulsion polymerization, the sulfonated monomer can be incorporated ineither the first stage or the second stage or both stages. The amount ofthe ionic group is preferably from about 200 to about 2500 EW, and morepreferably from about 200 to about 1100 EW, wherein EW is equivalentweight and is the number of grams of polymer per sulfonated unit. Otheramounts can be used.

The polymer of the present invention which contains at least one acrylicor vinyl resin or both having at least one ionic or ionizable group canhave an equivalent weight with respect to the acrylic or vinyl resin offrom about 200 to about 8,000, such as from about 900 to about 1,400.This equivalent range can provide preferred properties with respect tomembrane formation and the ability to avoid the need for fluoropolymers,as an option. The polymer of the present invention can optionally beformed as a blend. Preferably, the polymer of the present invention iscrosslinked using conventional crosslinking techniques.

Crosslinking can be done via conventional methods including, but notlimited to, self-condensation, addition of a secondary crosslinker, orradiation crosslinking. These are well described in the literature andwell known in the art. Examples of monomers able to undergo selfcondensation crosslinking include N-methylol acrylamide, isobutoxymethacrylamide, N-methylenebisacrylamide, and glycidyl methacrylate.Examples of secondary crosslinkers include free and blocked isocyanates,melamines, epoxies, carboxylates, carboxylic acids, alkoxy silanes,silicones, aziridines, and carbodiimides. Catalysts which can be chosenfor the specific crosslinking chemistry and would include organotins,sulfonic acids, or amines. Examples of radiation crosslinking includeelectron beam, ultraviolet, and gamma radiation.

The polymerization of the mixture of polymerizable vinyl and/or acryliccontaining monomers can be carried out separately and then blended withone or more polymer(s), or polymerized in the presence of one or morepolymers. The polymerization of the vinyl and/or acrylic containingmonomers can be prepared by solution, bulk, emulsion polymerizations, orany other known polymerization methods.

If the polymerization of the mixture of polymerizable vinyl and/oracrylic ionic containing monomer is carried out separately, and thenblended with one or more polymers, the blending can be carried outthrough various conventional ways including, but not limited to,solution blending, extrusion blending, latex blending, and the like. Forsolution blending, the polymer can be dissolved or dispersed in asolvent. The solvent used for the polymer can be similar or differentthan the solvent used for the acrylic/vinyl ionic containing polymer.For example, the blending could involve two solventsolutions/dispersions, or a powder added to a solventsolution/dispersion, or the two polymers in the same solvent, or anyother combination. Typical solvents used include tetrahydrofurane,acetone, dimethylsulfoxide, dimethylformamide, N-methyl pyrrolidinone.For melt extrusion blending, typical extrusion temperatures rangebetween about 100° C. to about 300° C., preferably from about 150° C. toabout 250° C. The material could be extruded such as in the shape ofpellets or films. For the case of latex blending, the mixing can takeplace under various conventional ways: the acrylic/vinyl latex can bemixed with the polymer latex, or the acrylic/vinyl polymer can bedispersed or dissolved in the polymer latex, or any other known mixing.The mixing could involve more than two latexes. The quantity and natureof each latex is adjusted in such a way that the physical and chemicalproperties expected are obtained, and the expected EW is obtained. Inthe case of a waterborne membrane (e.g., prepared by direct latex case)the particle size and solids content of one or more latexes can betailored to the desired properties.

For solvent polymerization, the polymerization can take place usingconventional techniques. In the case of a blend with another polymer,the solvent used for the polymer blend can be similar or different thanthe solvent used for the acrylic/vinyl polymer. For example, theblending could involve two solvent solutions/dispersions, or a powderadded to a solvent solution/dispersion, or the two polymers in the samesolvent, or any other combination. Typical solvents used includedimethylsulfoxide, dimethylformamide, N-methyl pyrrolidinone,isopropanol, methanol, and the like.

The emulsion polymerization can be carried out under the same conditionsas for conventional emulsion polymerizations. A surfactant, apolymerization initiator, a chain transfer agent, a pH regulator, andeventually a solvent and a chelating agent, are preferably added to theseed latex, and the reaction is carried out under suitable reactionconditions of sufficient pressure, temperature, and time, such as underatmospheric pressure, from about 0.5 to about 6 hours at temperaturestypically of from about 20 to about 150° C., more preferably from about40 to about 80° C.

In the case of a particle, the particle can have a particle size of fromabout 90 or less to about 500 nm or more, and more preferably from about50 to about 300 nm, wherein the amount of polymer is from about 5 toabout 95 weight % and the amount of the acrylic or vinyl resin is fromabout 95 to about 5 weight %. The emulsion polymerization can beperformed according to standard methods: batch polymerization using themonomer dispersion from the beginning; semi-continuous polymerization,wherein part of the monomer mixture is fed continuously or in batches;and continuous polymerization wherein the monomer mixture is fedcontinuously or in batches in the aqueous polymer dispersion during thereaction.

The surfactant can be anionic, cationic, and/or non-ionic surfactants,and/or amphoteric surfactants. The surfactant can be used separately orin combination with two or more. Examples of the anionic surfactantinclude esters of higher alcohol sulfates (e.g., sodium salts of alkylsulfonic acids, sodium salts of alkyl benzenesulfonic acids, sodiumsalts of succinic acids, sodium salts of succinic acid dialkyl estersulfonic acids, sodium salts of alkyl diphenylether disulfonic acids).Examples of the cationic surfactant include an alkyl pyridinium chlorideor an alkylammonium chloride. Examples of the non-ionic surfactantinclude polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylesters, polyoxyethylene alkyl esters, polyoxyethylene alkylphenylesters, glycerol esters, sorbitan alkylesters, and derivatives thereof.Examples of the amphoteric surfactant include lauryl betaine. Reactiveemulsifiers, which are able to copolymerize with the above-mentionedmonomers, can also be used (e.g., sodium styrene sulfonate, sodiumalkylsulfonate, sodium aryl alkylsulfonate and the like). The amount ofsurfactant usually used is from about 0.05 to about 5 parts by weightper 100 parts by weight of total polymer particles, though other amountscan be used.

Any kind of initiator which produces radicals suitable for free radicalpolymerization in aqueous media, preferably for temperatures from about20 to about 100° C., can be used as the polymerization initiator. Theycan be used alone or in combination with a reducing agent (e.g., sodiumhydrogenobisulfite, sodium thiosulfate, sodium hydrogenosulfite). Forexample, persulfates and hydrogen peroxide can be used as water-solubleinitiators, and cumene hydroperoxide, diisopropyl peroxy carbonate,benzoyl peroxide, 2,2′-azobis methylbutanenitrile,2,2′-azobisisobutyronitrile, 1,1′-azobiscyclohexane-1-carbonitrile,isopropylbenzenehydroperoxide can be used as oil-soluble initiators.Preferred initiators include 2,2′-azobis methylbutanenitrile and1,1′-azobiscyclohexane-1-carbonitrile. The oil-soluble initiator ispreferably dissolved in the monomer mixture or in a small quantity ofsolvent. The amount of initiator used is preferably from about 0.1 toabout 2 parts by weight per 100 parts by weight of the monomer mixtureadded.

Any suitable type of chain transfer agents can be used, and preferablyone that does not considerably slow down the reaction. The chaintransfer agents that can be used include, for example, mercaptans (e.g.,dodecyl mercaptan, octylmercaptan), halogenated hydrocarbon (e.g.,carbon tetrachloride, chloroform), xanthogen (e.g., dimethylxanthogendisulfide), and the like. The quantity of chain transfer agent used isusually from about 0 to about 5 parts by weight per 100 parts by weightof the monomer mixture added.

Any suitable type of pH adjusting agents can be used. The pH adjustingagents that can be used include, for example, sodium carbonate,potassium carbonate, and sodium hydrogenocarbonate, and the like. Thequantity of pH adjusting agent used is usually from about 0 to about 2parts by weight per 100 parts by weight of the monomer mixture added.

A small quantity of solvent can be added during the reaction, forinstance, in order to help the seed particle swelling (if this is used)by the monomer (and therefore, increase the mixing at a molecular level)and improve film formation. The quantity of solvent added should be insuch ranges that workability, environmental safety, production safety,and/or fire hazard prevention are not impaired. The solvents usedinclude for example, acetone, methylethyl ketone, N-methyl pyrrolidone,toluene, dimethylsulfoxide, and the like.

One advantage of the present invention is the introduction of at leastone ionic or ionizable moiety, such as a sulfonated moiety, to thepolymer by copolymerization of a monomer containing the ionic orionizable group, optionally with other monomers, in the presence of apolymer aqueous dispersion. Consequently, in the present invention, theionic or ionizable functionality is chemically bonded to the polymerchain via polymerization thus avoiding grafting techniques.

In addition, the present invention optionally permits an intimateblending of two or more polymers in the dispersion (e.g., aqueousdispersion), preferably through the use of the seeded polymerizationmethod or methods. Accordingly, the resulting resin can be an intimateblend of at least one polymer and at least one polymer bearing the ionicor ionizable group. Thus, the need for grafting techniques can beavoided as well as the need to use environmentally unfriendly solventsolutions. Moreover, there is no need for post-sulfonation of the resinusing acids such as sulfuric and sulfonic acids or derivatives thereof,since the ionic or ionizable group, e.g., the sulfonated group, isalready on the monomer. Furthermore, because the ionic or ionizablegroup is preferably polymerized, its distribution along the polymerchain is easily controlled by conventional means known in the art suchas shot addition, continuous feed, late addition, and the like.Consequently, the resulting ionic or ionizable group distribution in amembrane formed from the polymer blend can be more easily controlledthan previously. Accordingly, the tailoring of various properties, suchas homogeneous, random, heterogeneous, and the like, can be achieved.

In the previous technology, when the polymer blend containing the atleast one acrylic resin or vinyl resin having at least one ionic orionizable group was blended with at least one polymer, such as athermoplastic fluoropolymer, the acrylic resin or vinyl resin phase wasnot as compatible with the fluoropolymer as desired. As a result, domainsizes of above 1,000 nm were common, which also contributed toconductivity which was not as optimal as desired. In the presentinvention, techniques have been created to dramatically decrease thedomain sizes of the acrylic resin or vinyl resin in the additionalpolymer such that the phases are compatible to the point where thedomain sizes are less than 1,000 nm, such as 500 nm or less and in manycases significantly below 100 nm to the point where the domains arebarely detectable, if detectable at all, such as shown in FIG. 2 of thepresent application.

One way to achieve this improvement is to form the acrylic resin orvinyl resin having the at least one ionic or ionizable group asdescribed above and to then treat this acrylic resin or vinyl resin inorder to have an ammonium counterion and/or phosphonium counterionassociated with the ionic or ionizable groups. In many embodiments, theionic or ionizable group that is present with respect to the acrylicresin or vinyl resin is in the form of an acid or salt. In order toachieve a type of ion exchange, the acid form is neutralized to form asalt. This is achieved by adding an ammonium compound (e.g., that willgenerate an ammonium ion) or phosphonium compound (e.g., that willgenerate a phosphonium ion) such as the ones described in detail below.The amount of the ammonium compound or phosphonium compound can be anyamount sufficient to achieve the desired level of ionic exchange or saltformation. For instance, the ammonium or phosphonium compound can beadded to neutralize from about 40% or less to about 100% and morepreferably from 70% to about 95% by wt. of the ionic or ionizablegroups. The ammonium or phosphonium compound can be added in any fashionsuch as simply mixing in the ammonium or phosphonium compound with theacrylic resin or vinyl resin. The ammonium or phosphonium compound canbe in any form, and is preferably in the form of a solid or liquid andmore preferably a liquid. The ionic exchange or treatment can occurprior to, during, and/or after blending with the additional polymer.Once the ammonium or phosphonium compound has been added and the salthas formed and after film or membrane formation, the salt can then beconverted back to its original state, which as stated above, in mostinstances is an acid form. This can be achieved by introducing an acid,which is preferably a strong acid, such as sulfuric acid, to the polymerblend which will then cause the reformation of the acid (e.g.,protonated). An alkali metal, alkaline earth metal hydroxide, an aqueoussolution, diluted H₂SO₄, diluted HCl, and the like can be used insteadof a strong acid. The reformation can be done to completely remove orsubstantially remove (e.g., 95% by wt. or higher removal) the ammoniumor phosphonium salt or can be partially removed to any degree desired.The film or membrane can then be washed using various techniques toremove the ammonium and/or phosphonium compound as well as any acidresidue. This can simply be done by using water such as deionized waterand the like. The film or membrane can be cross-linked before or afterthe ammonium or phosphonium compound (e.g., salt) has been removed. Thefilm or membrane is preferably cross-linked using any conventionalcross-linking technique, such as those exemplified above. Thiscross-linking may aid in ensuring that the acrylic resin or vinyl resinis locked into place with respect to the polymer blend. This permitsimproved conductivity and ensures that the phase compatability betweenthe polymers is maintained, especially over time. The removal of theammonium and/or phosphonium counterion preferably occurs after formationof the film or membrane. In lieu of these counterions, any counterionsthat permit the same effect can be used. The present invention permits amore uniform dispersion of the polymer blend and provides greatlyimproved conductivity and greatly improved smaller domain sizes asdescribed above. In the art, domain sizes are also sometimes referred toas clusters or ionic clusters. In either case, the present inventionpermits these domains or clusters to be greatly minimized or reduced insize such that they are about 500 nm or less and are preferably barelydetectable in preferred embodiments as shown in FIG. 2.

With respect to the ammonium compound, the ammonium compound preferably,as described above, forms a counterion to the ionic or ionizable group.This counterion is considered an ammonium counterion and more preferablyan alkyl ammonium counterion and even more preferably an alkylquaternary ammonium counterion. Preferably, the alkyl groups of theammonium counterion are C₁-C₆ alkyl group though other alkyl ammoniumscan be used. In addition, more than one different type of counterion canbe formed such as two or more different types of ammonium counterions.The same is true for the phosphonium counterions. This can beaccomplished by using two or more different ammonium and/or phosphoniummaterials to form different ions or a mixture of various ions.

As stated above, and strictly as an example, the sulfonated orphosphonated resins in either acid or salt form can be mixed with theammonium compound (e.g., salt), such as an organic quaternary ammoniumcompound to thereby convert the resin to an ammonium salt. This step canbe repeated several times to achieve satisfactory conversion of theresin to the ammonium salt. Examples of suitable ammonium salts include:tetramethylammmonium, tetraethylammonium, tetrapropylammonium,tetrabutylammonium, tetrapentylammonium, tetrahexylammonium,benzyltrimethylammonium, benzyltriethylammonium, hexamethonium,decamethonium, cetyltrimethylammonium, decyltrimethylammonium,dodecyltrimethylammonium, and methyltributylammonium. Preferably theammonium salt has a molecular weight of at least 186. Mixtures of theammonium salts can be utilized in the process. The ammonium can containorganic groups in a quaternary ammonium salt of the formula N R₁R₂R₃R₄⁺, wherein R₁-R₄ are independently selected from C₁-C₃₀ alkyl, aryl,aralkyl or cycloalkyl groups. The phosphonium analogs of the ammoniumsalts can also be used, such as tetraalkyl phosphonium salts and like.

As stated, the ammonium or phosphonium salt containing resin can beprocessed using conventional methods to prepare a film or polymermembrane. The film or polymer membrane can then preferably be processedto remove all or most of the ammonium and/or phosphonium cation andconvert the film or membrane back to its original form (e.g., acid orsalt form). This step can be achieved by exposing the film or polymermembrane to a solution of an alkaline metal or alkaline earth metalhydroxide or an aqueous acid solution, such as sulfuric acid orhydrochloric acid. In some cases this step can be repeated to achievesatisfactory conversion of the ammonium or phosphonium salt back to theacid or salt form or other desirable form.

Furthermore, due to these various advantages described above, theapplications of the present invention can include, but are not limitedto, films, membranes, fuel cells, coatings, ion exchange resins, oilrecovery, biological membranes, batteries, and the like.

A polymeric ion membrane or polyelectrolyte membrane can be made fromthe polymers of the present invention. The polymeric ion membrane can beprepared from conventional film preparation methods, such as meltextrusion, solvent cast, latex cast, and the like. Membrane electrodeassemblies can be made from the membranes of the present invention andfuel cells using this membrane electrode assembly can be prepared. Inusing the polymers of the present invention to form membranes, thepolymer can have any equivalent weight and preferably has an equivalentweight of from about 200 to about 8,000, and preferably from about 200to about 1,500 and even more preferably from about 200 to about 1,400,with respect to the ionic acrylic or vinyl resin present in the polymer.

In more detail, the compositions of the present invention are especiallyuseful in fuel cells, batteries, and the like. The design and componentsused in the fuel cell and batteries would be the same as in conventionalfuel cells and batteries except using the compositions of the presentinvention in the formation of the polymeric ionic exchange membrane.Accordingly, the designs and manners of making the fuel cells andbatteries as described in U.S. Pat. No. 5,795,668, EP 1 202 365 A1, PCTPublication No. WO 98/22989, WO 02/075835, and WO 98/20573, Lin et al.,Journal of Applied Polymer Science, Vol. 70, 121-127 (1998) can be usedin the present invention and are fully incorporated herein in theirentireties by reference. The membrane can be used alone or withconventional fillers, such as silica and the like. The fuel cell may usea liquid or gaseous fuel such as a liquid hydrocarbon like methanol. Thefuel cell of the present invention is capable of operating at a widerange of operating conditions. The fuel cell of the present inventioncan have a porous support layer and an ion exchange resin wherein theion exchange resin is supported on at least one side of the poroussupport layer. The present invention can be useful in direct methanolfuel cells or other fuel cells. Preferably, the fuel cells of thepresent invention have low fuel crossover, high electric conductivity,and/or high mechanical strength. The thickness of the membrane can beconventional but is preferably from about 0.5 to about 10 mils and morepreferably from about 1 mil to about 5 mils. Further, the membranepreferably has an equivalent weight of from about 200 to about 2500, andmore preferably about 200 to about 1400. The porous support layer can bemade from any conventional material such as a fluoro-containing polymeror other hydrocarbon containing polymers such as polyolefin. The poroussupport layer has conventional parameters with respect to pore diameter,porosity, and thickness. The fuel cells of the present inventionpreferably have excellent electrical properties and relatively lowelectrical resistance.

Certain perfluorinated polymeric ion exchange membranes, are well knownin the field for providing high cation transport, and have beenextensively used as ion exchange membranes. Polymeric ion exchangemembranes are referred to as solid polymer electrolytes or polymerexchange membrane (PEM).

The most commonly used membrane, and commercially available, are Nafion®and Aciplex®. They are perfluorinated sulfonated ionomers, commonlyreferred to as PFSI. The PEM which are based on the PFSI membranegenerally suffer from the following short comings.

-   -   i) Poor mechanical properties leading to failure and cracking.    -   ii) Limited temperature window in which the cell can be        operated, which leads to problems of water management, CO        poisoning, and the like.    -   iii) High cost.    -   iv) Limited range of EW allowed.    -   v) Lack of possibility to crosslink.

Because in PFSI, the ionomer and the polymer matrix (PTFE) arecopolymerized, there is a limited range of EW and mechanical propertiesachievable since a change in ionomer amount will directly affect thepolymer matrix and vice versa. By blending the ionomer with the polymermatrix, there is a greater possibility to achieve a wide range of EWindependently of the polymer matrix. It is then possible to obtain amembrane with low EW while maintaining good mechanical properties.

When used for fuel cell or battery applications, the membrane sits in avery acidic medium at temperatures that could reach 150° C., and inpresence electrochemical environment, solvents and the like, thusrequiring high chemical and electrochemical resistance. Thoserequirements are often met when a perfluorinated membrane is usedbecause perfluorinated materials have inherent chemical andelectrochemical resistance. However, there are very fewnon-perfluorinated polymer electrolyte membranes described in theliterature that meet these requirements.

For applications where the fuel is a liquid fuel, the barrier propertiesof the membrane toward that fuel are critical. For example, in directmethanol fuel cell, the fuel can be a dilute (1M to 4 M) methanolaqueous solution. Very few membranes can meet the needed barrierproperties.

The membrane's mechanical strength is an important property for battery,chlor-alkali cell, and fuel cell applications. Indeed the membrane isoften subject to high differential pressures. In addition, themechanical strength becomes critical when the membrane is very thin(less than 100 microns). However, the commercially available PFSImembranes show limited mechanical properties and often fail or crackduring cell operation leading to irreversible damage. There are manyways to overcome this problem. By blending the ionomer in a polymermatrix that has good mechanical strength, it is possible to prepare amembrane with high proton conductivity and good overall mechanicalproperties.

In order to enhance the mechanical and chemical properties of a polymer,an easy and efficient route is to crosslink. However, in PFSI this isvery difficult to achieve since fluorinated monomers and perfluorinatedionomers do not readily copolymerize with non perfluorinated functionalmonomers. And there are no or very few perfluorinated functionalmonomers commercially available. In the present invention, the polymerblend allows for copolymerizing a functional monomer with the ionomer,or adding a crosslinkable polymer or monomer to the blend. This leads toan easy way of crosslinking if required.

Most of the membranes for DMFC application described in the literatureface the problem of trade off between low areal resistance and lowmethanol crossover. Most of them display high areal resistance whenmethanol crossover is low, and vice versa. For example, addition ofadditives such as fillers or PTFE fibrils into a Nafion type membranehelps indeed to lower the methanol crossover, but leads to an increaseof the areal resistance because the additive is not proton conductive.Ideally, one would like low areal resistance (highest proton transport)and low methanol crossover. This is illustrated in the following Tablesbased on open literature data. As can be seen, although a significantdecrease in methanol crossover is achieved, it comes with a trade off oflower conductivity. In order to allow for comparison with the presentinvention, the areal resistance has calculated based on data from thereference paper. TABLE 1 Properties of partially sulfonatedpoly(styrene) membranes, from N. Carretta, V. Tricoli, F. Picchioni, J.Memb. Sci., 166 (2000) 189. IEC Wet thick. σ22° C. D @ 22° C. Membraneeq/g μm mS/cm 10⁻⁶ cm²/s Nafion 117 0.90 216 75.9 1.30 SPS 15 1.24 1051.5 0.027 SPS 18 1.34 233 32 0.52 SPS 20 1.41 338 50 0.52 * obtainedfrom V. Tricoli, J. Electrochem. Soc., 145 (1998) 3798. Wet R J^(b) IECthick. σ22° C. 22° C.^(b) D 22° C. 10⁻¹⁶ Membrane Meq/g μm mS/cm Ω/cm²10⁻⁶ cm²/s mol/cm²/s Nafion 117^(a) 0.90 216 75.9 0.28 1.30 6.02 SPS 151.24 105 1.5 7.00 0.027 0.26 SPS 18 1.34 233 32 0.61 0.52 2.65 SPS 201.41 338 50 0.68 0.52 1.54 ^(a)V. Tricoli, J. Electrochem. Soc., 145(1998) 3798. ^(b)Calculated from the values given by Carretta et al.

TABLE 2 Properties of partially sulfonatedpolystyrene-block-poly(ethylene- ran-butylene)-block-polystyrenemembranes, from J. Kim, B. Kim, B. Jung, J. Memb. Sci., 166 (2000) 189.Wet thick. σ D Membrane μm mS/cm 10⁻⁶ cm²/s Nafion 117 ˜220 30 2.60 15%SSEBS 313 1.3 0.021 22% SSEBS 287 18 0.65 34% SSEBS 274 32 0.12 47%SSEBS 342 45 0.26 J* Wet thick. σ R* D 10⁻¹⁶ Membrane μm mS/cm Ω/cm²10⁻⁶ cm²/s mol/cm²/s Nafion 117 ˜220 30 0.73 2.60 11.8 15% SSEBS 313 1.324 0.021 0.07 22% SSEBS 287 18 1.59 0.65 2.26 34% SSEBS 274 32 0.86 0.124.38 47% SSEBS 342 45 0.76 0.26 7.60*Calculated from the values given by Kim et al.

Finally, another barrier is the limitation in cell temperature. This isessentially due to the inherent chemical structure of the polymer, whichis based on copolymerization of TFE and a perfluorinated sulfonatedmonomer. And it is well known that PTFE does not have good mechanicalresistance at high temperatures. Because the commercially available PFSIloose their mechanical properties at elevated temperatures, the currentcell operational temperature is between 65-80 C. This leads to verydifficult water management problems. In order to have a fuel cell thatdoes not require expensive and cumbersome equipment to manage waterflows, a membrane that can withstand higher temperatures is required.

In order to overcome the limits mentioned above, and develop a membranethat could be used for application in fuel cells, synthesis of a novelpolymer polyelectrolyte membrane became the focus. In one embodiment, anovel polymer electrolyte membrane was developed in which:

-   -   a) The ionomer (polyelectrolyte) is not perfluorinated.    -   b) The PEM is a blend between a polymer and an ionomer.    -   c) By properly choosing the pair polymer/ionomer, superior        mechanical properties can be achieved. The resulting        polyelectrolyte membrane has high mechanical strength.    -   d) By properly dispersing the ionomer in the polymer matrix, it        is possible to achieve superior properties.    -   e) By properly selecting the nature and amount of counter ion        used in the membrane preparation superior properties are        obtained.    -   f) By making a multi-layer membrane, the selectivity to alcohols        can be enhanced, in particular methanol selectivity, while        maintaining all other key properties.    -   g) Unlike most membranes described in the literature, the        present membrane displays both a low methanol crossover and a        low areal resistance. This is achieved by using the        polyelectrolytes of the present invention.

By properly selecting the non-perfluorinated ionomer resin, thefluoropolymer matrix, and the nature of the counter ion used in themembrane preparation, one preferably obtains a membrane which overcomesone or more of the PFSI shortcomings.

By the present invention, one can have a direct control of the ionic(e.g., sulfonated) group location (unlike sulfonation by graftingtechniques) and the present invention can use commercially availablemonomers, thus avoiding very complex steps to prepare “sulfonedperfluorinated ionomers”. The resulting process is also very simple asopposed to processes used to prepared perfluorinated sulfonated ionomerssuch as Nafion® or Aciplex®.

In one embodiment, the polyelectrolyte membrane is formed from acomposition that contains at least one acrylic and/or vinyl resin orboth having at least one ionic or ionizable group. Preferably, at leastone ammonium counterion and/or phosphonium counterion is also presentwith the at least one ionic or ionizable group. Furthermore, at leastone additional polymer is also present. Preferably, the at least oneionic or ionizable group is present in an amount of from about 200 toabout 2,500 EW. As stated above, the counterion is removed (e.g.,converted back to acid form). In one embodiment, the polyelectrolytemembrane is quite useful with fuel cells including fuel cells powered bydirect fuel such as direct methanol fuel cells or polymer electrolytefuel cells. The present invention preferably provides an improvedreduced fuel crossover such as reduced methanol crossover. In addition,or alternatively, the present invention further provides a membrane thathas a reduced areal resistance. Furthermore, the thickness of themembrane can be significantly reduced by way of the present inventionand yet achieve reduced fuel crossover and/or reduced areal resistance.

In addition, and as an option, the membrane can have one layer ormultiple layers. Each layer can be the same or different from the otherlayers. By using a multi-layer membrane, one can achieve varying degreesof fuel (e.g., methanol) selectivity and proton conductivity. Each layercan have the same or different chemical composition, thickness, or beformed with different amounts and types of an ammonium and/orphosphonium counterion. By using a multi-layer membrane construction,reduced fuel crossover can even be more improved.

The multi-layer membrane of the present invention can be prepared anynumber of ways. Each individual layer can first be prepared as describedabove using conventional casting or other layer forming techniques.These layers can then be combined to form a multi-layer membranestructure. The layers can be adhered together or attached together byother means commonly used to form laminate structures. In addition, onelayer can be formed and then a second layer can be casted onto thepreviously layer to form the second layer and so on to form the desirednumber of layers. The multi-layer structure of the present invention canhave two layers, three layers, four layers or more. Each layer of themulti-layer polyelectrolyte membrane can be formed in the same manner orby different manners. Thus, each layer of the multi-layerpolyelectrolyte membrane can be formed by extrusion, solvent cast, latexcast, or other film preparation techniques. One layer can be extruded,for instance, and another layer can be casted as so on. Also, anylamination technique of combining polymeric layers can be used to formeach layer. Accordingly, any combination of formation of layers can beused in the present invention to form the multi-layer structure.

The multi-layer polyelectrolyte membrane of the present invention canhave one or more layers which contain the polyelectrolyte of the presentinvention. Also, an option, one or more layers of this multi-layermembrane can contain other polyelectrolytes that are commerciallyavailable such as Nafion®, Flemion® and Aciplex® polymers or otherperfluoronated materials. For purposes of the present invention, atleast one of the layers contains the polyelectrolyte of the presentinvention.

Preferably, the polyelectrolyte membranes of the present inventionachieve a methanol crossover, when used in a fuel cell, of 5×10⁻¹⁶mol/cm²/s or lower and more preferably 3×10⁻¹⁶ mol/cm²/s or lower, andeven more preferably 1×10⁻¹⁶ mol/cm²/s or lower. Suitable ranges caninclude from about 0.01×10 ⁻¹⁶ mol/cm²/s to about 3×10⁻¹⁶ mol/cm²/s.Other ranges are possible. In addition, or in the alternative, thepolyelectrolyte membranes of the present invention when used in a fuelcell can have an areal resistance of about 0.3Ω/cm² or less andpreferably about 0.1Ω/cm² or lower. Suitable ranges include from about0.1 to about 0.3Ω/cm².

As stated above, fuel cells, batteries, and the like can be used andincorporate the polyelectrolyte compositions of the present invention inthe form of a membrane or other shape.

In all the tables, the quantities of monomer and seed particles aregiven in weight percent, unless otherwise specified.

Proton Conductivity Measurements:

Proton conductivity was measured in a 4 probes configuration using aGamry Instruments that posses a PC4 750 potentiostat an a EIS 300 systemto run Electrochemical Impedance Spectroscopy. Measurements areperformed (after boiling the membrane in water for 1 hour) under liquidwater at different temperatures. By using the resistance R determined bythe EIS measurement, the conductivity a is calculated using the formulabelow: $\sigma = \frac{d}{w \times t \times R}$where w: width of the film, d: distance between the inner electrodes, R:Resistance of the film. Areal resistance: The areal resistance gives anindication of conductivity per unit of thickness, hence taking intoaccount the membrane resistance. The areal resistance is given in Ωcm².The area Resistance R_(a) is expressed as a function of the protonconductivity σ and the thickness t as: $R_{a} = {\frac{t}{\sigma}.}$Note that this area resistance is different from the surface resistanceR typically used in microelectronics or glass coating industry andexpressed in Ω/square cm as: $R_{S} = {\frac{1}{t \times \sigma}.}$

Methanol/Ethanol Permeation Measurement

The methanol concentration is monitored continuously using adifferential refractometer Waters 410. The flow rate used was 2mL/min.The methanol aqueous concentration used was generally 1 mol/L.

Permeability Coefficient D:

A membrane diaphragm cell (E. L. Cussler, Diffusion, 2^(nd) ed.,Cambridge University Press, Cambridge, 1997) was used to measuremethanol diffusion coefficient. The membrane methanol diffusioncoefficient D is expressed as: $\begin{matrix}{D = {\frac{1}{\beta \times t} \times {\ln\left( \frac{C_{0}^{B} - C_{0}^{A}}{C_{t}^{B} - C_{t}^{A}} \right)}}} & (1)\end{matrix}$Where β(cm⁻²): diaphragm-cell constant,${\beta = {\frac{A}{l} \times \left( {\frac{1}{V^{A}} - \frac{1}{V^{B}}} \right)}},$t; time (s), C₀ ^(A) and C₀ ^(B): initial methanol concentrations inboth compartments (mol/L), C_(t) ^(A) and C_(t) ^(B): methanolconcentrations in both compartments at t (mol/L), V^(A) and V^(B):volumes of the two cell compartments (cm³).Methanol Flux:

The flux J of methanol across the membrane is defined by:$J = {\frac{D}{l} \times \left( {C_{0} - C} \right)}$where D: methanol diffusion coefficient of the membrane, l: membranethickness and (C₀—C): concentration gradient through the membrane.Selectivity:

In the DMFC field, membrane selectivity a is a key criterion used toqualify a membrane. This selectivity is define as:$\alpha = \frac{\sigma}{D}$where σ; membrane conductivity and D: methanol diffusion coefficient.

The present invention will be further clarified by the followingexamples which are intended to be purely exemplary of the presentinvention.

EXAMPLES

The compositions of the present invention were made using the followingmaterials and reaction conditions:

The synthesis of the ionomer is described in and PCT Publication No. WO01/60872, the entire disclosure of which is incorporated herein byreference.

The films were cast on glass substrates using a blade type applicatorand cured in an oven at temperatures ranging from 150° C. to 200° C.,for 1 to 15 minutes.

Raw Materials

Monomers (ATOFINA Chemicals, Inc., Aldrich), initiators (Aldrich,DuPont), surfactants (Aldrich) and buffers (Aldrich) were used withoutfurther purification.

Desmodur BL-3175A is a hexamethylene diisocyanate oligomer blocked withmethyl ethyl ketoxime, and is a product of Bayer Corp.

Example 1

An ionomer solution in NMP (25% by weight) of SEM/HEMA/MMA/Styrene (10.8g) (EW=278), 2.75 g of a 55% water solution of TBAOH (available fromSachem) and 40.31 g of NMP were added with mixing to a reactor vesselequipped with appropriate inlets and equipment. To 20.16 g of thissolution, 2.36 g of Kynar 2801 (ATOFINA Chemicals) powder were addedwhile stirring at 60° C. until dissolution. Once a homogeneous solutionwas obtained, 0.52 g of Desmodur BL3175A isocyanate cross-linker (Bayer)and 0.02 g of DBTDL catalyst are added with mixing. The solution waspoured on a glass plate, spread with a doctor knife and baked for 7minutes at 177° C. The film membrane was protonated by treatments withone molar hydrochloric (HCl) and sulfuric (H₂SO₄) acids for 2 hours eachat 65° C., then rinsed with deionized water. The proton conductivity ofthe membrane, measured by AC impedance, was 30 mS/cm and the arealresistance at 25° C. is 0.15 Ω/cm².

Examples 2 -7

Same preparation procedure as Example 1 above. Amounts of reactants andtesting results presented in Tables 3, 4 and 5.

Example 8

A NMP solution of polyelectrolyte in TBA form was prepared as follows:to 6428 g of a 25 wt % solution of polyelectrolyte in NMP, 2204 g TBAOH(55% in water) were added and the water removed. Then 4445 g NMP wereadded. To 6051 g of this solution were added 1878 g Kynar 2801 and 7149g of NMP and stirred until dissolution. To 41.05 g of thepolyelectrolyte/Kynar solution in NMP described above, 0.39 g ofDesmodur N3300 isocyanate cross-linker (Bayer) were added with mixing.The solution was poured on a glass plate, spread with a doctor knife andbaked for 7 minutes at 177° C. The membrane was protonated by treatmentswith one molar hydrochloric (HCl) and sulfuric (H₂SO₄) acids for 2 hourseach at 65° C., then rinsed with deionized water. The protonconductivity of the membrane, measured by AC impedance, was 60 mS/cm andthe areal resistance at 25° C. is 0.06 Ω/cm².

Example 9

Same as Example 8 above but without addition of an isocyanatecrosslinker. The proton conductivity of the membrane, measured by ACimpedance, was 60 mS/cm and the areal resistance at 25° C. is 0.06Ω/cm².

Example 10

Same preparation procedure as Example 8 above. Amounts of reactants andtesting results presented in Tables 3, 4 and 5.

Comparative-Example 11

An ionomer solution in NMP (25% by weight) of SEM/HEMA/MMA/Styrene (5.62g) (EW=278), 0.39 g of a 48% water solution of NaOH and 25.80 g of NMPwere added to a reactor vessel with mixing. To this solution, 3.65 g ofKynar 2801 (ATOFINA Chemicals) powder was added while stirring at 60° C.until dissolution. Once a homogeneous solution was obtained, 0.80 g ofDesmodur BL3175A isocyanate cross-linker (Bayer) and 0.04 g of DBTDLcatalyst are added with mixing. The solution was poured on a glassplate, spread with a doctor knife and baked for 7 minutes at 177° C. Themembrane was protonated by treatments with one molar hydrochloric (HCl)and sulfuric (H₂SO₄) acids for 2 hours each at 65° C., then rinsed withdeionized water. The proton conductivity of the membrane, measured by ACimpedance, was 6 mS/cm and the areal resistance at 25° C. is 0.53 Ω/cm².

Example 12

Same preparation procedure as Example I above. Upon addition ofcrosslinker solution turned black and preparation was stopped. Amountsof reactants presented in Tables 3 and 4.

Comparative-Example 13

Same preparation procedure as Example I above, but no organic quaternaryammonium salt was added. Amounts of reactants and testing resultspresented in Tables 3, 4 and 5. TABLE 3 Preparation of polyelectrolytesolutions Polyelectrolyte Counterion Solution Solution Amount Solventconcentration Amount added Cation concentration added NMP Example # (wt%) (g) M+ (wt %) (g) (g) 1 25 10.80 TBAOH 55 2.75 40.31 2 25 5.63 TBAOH55 1.87 25.77 3 15 98.01 TBAOH 55 19.86 0 4 15 98.01 TBAOH 55 19.86 0 515 98.01 TBAOH 55 19.86 0 6 15 98.01 TBAOH 55 19.86 0 7 25 10.83 TPAOH40 3.93 38.99 8 25 8.76 TBAOH 55 3.00 24.17 9 25 8.76 TBAOH 55 3.0024.17 10 25 9.01 TBAOH 55 3.04 6 11 25 5.62 NAOH 48 0.39 25.80 12 255.62 TBAOH 55 2.66 25.67 13 25 6.30 none 0 0 4.21

TABLE 4 Preparation of polyelectrolyte/fluoropolymer blend solutions a =powder, b = 15 wt % solution in NMP Polyelectrolyte Solution KynarCrosslinking Agent Catalyst Ex. # (g) (g) Form (g) (g) 1 20.16 2.36 a0.52 0.02 2 33.27 0.37 a 0.82 0.03 3 16.76 15.05 b 0.98 0.05 4 16.7522.62 b 0.97 0.05 5 16.75 35.17 b 0.99 0.06 6 16.74 60.31 b 0.98 0.08 722.39 2.63 a 0.62 0.03 8 35.93 5.11 a 0.39 none 9 35.93 5.11 a none none10 18.046 35 b 1.16 0.05 11 31.81 3.65 a 0.8 0.04 12 33.95 3.68 aSolution turned black 13 10.51 24.5 b 0.86 0.06

TABLE 5 Proton conductivity of polyelectrolyte membranes at 25° C.Conductivity Areal resistance Example (mS/cm) (ohm/cm²) 1 30 0.15 2 300.12 3 90 0.07 4 90 0.06 5 50 0.12 6 40 0.11 7 50 0.08 8 60 0.06 9 600.06 10 42 0.09 11 6 0.53 13 8 0.51Experimental:

Conductivity measurements were performed with a four probe configurationby Electrochemical Impedance Spectroscopy. The measurements were carriedout between 5×10⁵ and 1 Hz with a Gamry instrument(Potensiostat—Galvanostat ZRAPC4/750 and EIS 300 software). The valuespresented here have been obtained under immersed conditions at roomtemperature.

Legend:

SEM Sulfoethyl methacrylate

Kynar 2801 PVDF copolymer

MMA methyl methacrylate

HEMA hydroxyethyl methacrylate

TBAOH tetrabutyl ammonium hydroxide

TPAOH tetrapropyl ammonium hydroxide

NaOH sodium hydroxide

NMP N-methylpyrrolidinone

DBTDL dibutyltin dilaurate

Example 14

The experimental procedure as described with respect to example 8 abovewas followed except for the chemistry and amounts as set forth in Table6 below. Table 6 further provides conductivity measurements obtained inthe same manner as above. TABLE 6 Neutral- Kynar Content Ratio ofConduc- izing Neutral- (wt % of total Crosslinking tivity Agent ization(%) polymer content) Functionalities (mS/cm) TBAOH 80 60 0.7 170 TBAOH80 60 0.9 169 TBAOH 80 60 1.1 140 TPAOH 95 65 0.7 152 TPAOH 95 65 0.9142 TPAOH 95 65 1.1 133

As can be seen from the above examples, the conductivity of thepolyelectrolyte membranes of the present invention as shown in examples1-10 and 14, for instance, are greatly higher than the conductivity setforth in examples 11 and 13 which are comparative examples. In addition,the resistance, as shown in Tables 3 and 4 was also greatly reducedusing the techniques and polymers of the present invention.

Example 15

In the following examples, the crosslinking agent was Desmodur BL3175Aisocyanate cross-linker from Bayer.

The catayst was dibutyltin dilaurate (DBTDL) catalyst from Atofina.

In formulation F1, the Kynar 2801 fluoropolymer was added in the form ofpowder.

Formulations F4 and F5 were prepared from solutions S4 and S5 which wereexchanged with a blend of 2 counter ions: TPAOH and TMAOH

Formulations F6 was prepared from solutions S6, which was exchanged witha blend of 2 counter ions: TBAOH and TPAOH

Formulations F9 was prepared from solutions S9, which was exchanged witha blend of 2 counter ions: TPAOH and TEAOH

Formulations F7 were prepared from solutions S7, which were neutralizedwith which was neutralized with the same level of TPAOH usually used butprepared with a higher fluoropolymer/polyelectrolyte ratio.

Formulations F15 to F18 were prepared from solutions S15 to S18respectively, and were neutralized with the same level of TPAOH usuallyused but prepared with various fluoropolymer/polyelectrolyte ratios.

Table 7 sets forth the various ingredients and amounts. Unless statedotherwise, the same procedures as described above in previous exampleswere followed. TABLE 7 Preparation of polyelectrolyte solutions Allpolyelectrolytes P1, P2 and P3 were added as 25 wt % solution in NMPPolyelectrolyte P1, P2 and P3 are of similar composition but differentbatches. Polyelectrolyte Counter ion Solution Solution Concen- Amountconcen- Amount Solvent tration added Cation tration added NMP Ex. # (wt%) (g) M+ (wt %) (g) (g) S1 P1 6037 TBAOH 55% 1083 12981 S2 P2 20.02TPAOH 40% 7.28 16.51 S3 P3 19.04 TPAOH 40% 6.99 15.07 S4 P2 20.01 TPAOH40% 3.65 14.62 TMAOH 25% 2.62 S5 P3 10.00 TPAOH 40% 1.90 7.60 TMAOH 25%1.32 S6 P2 12.00 TBAOH 55% 2.03 9.38 TPAOH 40% 2.18 S7 P2 15.13 TBAOH55% 5.11 10.86 S8 P3 13.01 TPAOH 40% 4.73 9.76 S9 P2 12.06 TPAOH 40%2.19 11.51 TEAOH 25% 3.23 S10 P3 35.02 TPAOH 40% 12.74 27.20 S11 P315.09 TMAOH 25% 3.92 10.74 S12 P3 15.01 TEAOH 20% 7.91 12.53 S13 P220.03 TEAOH 20% 10.63 17.03 S14 P2 20.05 TMAOH 25% 5.22 14.90 S15 P39.55 TPAOH 40% 3.46 7.00 S16 P3 25.04 TPAOH 40% 9.11 18.91 S17 P3 19.04TPAOH 40% 6.99 15.07 S18 P3 25.05 TPAOH 40% 9.32 23.85

Table 8 sets forth the preparation of the polyelectrolyte using thesolutions of Table 7 TABLE 8 Preparation ofpolyelectrolyte/fluoropolymer blend solutions The fluoropolymer used inthese examples was Kynar 2800 fluoropolymer. a = powder, b = 15 wt %solution in NMP Polyelectrolyte fluoropolymer Crosslinking Catalyst Ex.# Solution Weight (g) (g) Form Agent (g) (g) F1 S1 16789 1874 a 342 16F2 S2 37.61 77.8 b 2.18 0.15 F3 S3 34.8 73.92 b 2.14 0.12 F4 S4 35.577.81 b 2.48 0.13 F5 S5 17.82 38.91 b 1.09 .017 F6 S6 22.19 46.76 b 1.260.08 F7 S7 28.10 100.05 b 1.64 0.15 F8 S8 23.60 86.70 b 1.42 0.12 F9 S921.69 46.72 b 1.26 0.08 F10 S10 63.46 136.12 b 3.80 0.23 F11 S11 25.1558.37 b 1.70 0.09 F12 S12 26.74 58.35 b 1.63 0.10 F13 S13 37.59 77.83 b2.27 0.12 F14 S14 34.77 77.80 b 2.15 0.14 F15 S15 17.31 89.85 b 1.080.12 F16 S16 45.56 62.55 b 2.69 0.12 F17 S17 34.8 73.92 b 2.14 0.12 F18S18 45.62 10.45 b 2.74 0.08

Table 9 sets forth the conditions for forming one or more layers of themembrane. TABLE 9 Examples Curing conditions for all membranes (orlayers): 7 min at 177° C., Air Flow = 1800 rpm excepted for M1 and M2: 6min at 127° C., Air Flow = 1300 rpm Second and third layer were eachapplied on dry film (wet on dry technique). Final Film layer 1 Filmlayer 2 Film layer 3 Membrane Blend Gap Blend Gap Blend Gap Dry Ex. #solution (μm) solution (μm) solution (μm) thickness M1 F1 330 — — — — 50M2 F1 660 — — — — 25 M3 F2 400 — — — — 26 M4 F3 400 — — — — 26 M5 F4 400— — — — 42 M6 F5 400 — — — — 40 M7 F6 400 — — — — 29 M8 F7 400 — — — —31 M9 F8 400 — — — — 27 M10 F9 400 — — — — 23 M11 F10 500 — — — — 44 M12F10 300 F11 110 — — 25 M13 F2 200 F13 400 — — 41 M14 F2 200 F2 250 — —25 M15 F10 300 F12 180 — — 30 M16 F2 200 F13 250 — — 30 M17 F2 200 F14250 — — 26 M18 F10 300 F12 110 — — 26 M19 F10 300 F11 180 — — 38 M20 F15200 F16 250 — — 31 M21 F17 100 F18 220 F17 150 42

Table 10 sets forth the properties of the membranes that were prepared.TABLE 10 Membranes properties Wet thick. σ25° C. R 25° C. D J Film μmmS/cm Ω/cm² 10⁻⁶ cm²/s 10⁻¹⁶ mol/cm²/s Nafion 112 61 97 0.06 0.51 8.37Nafion 117 221 95 0.23 0.99 4.50 Mono-layer M1 61 61 0.10 0.36 5.90 M228 62 0.04 0.23 8.38 M3 35 27 0.12 0.10 2.77 M4 37 42 0.08 0.17 4.59 M572 28 0.19 0.001 0.01 M6 99 29 0.3 0.002 0.02 M7 40 38 0.11 0.14 3.45 M831 35 0.09 0.11 3.48 M9 31 12 0.26 0.03 1.01 M10 36 21 0.19 0.12 3.51M11 63 36 0.13 0.21 3.41 Bi-layer M12 28 19 0.15 0.006 0.22 M13 66 220.28 0.09 1.36 M14 35 40 0.10 0.11 3.19 M15 42 43 0.09 0.13 3.14 M16 4240 0.11 0.11 2.57 M17 35 11 0.33 0.0007 0.02 M18 34 33 0.10 0.09 2.56M19 42 40 0.09 0.005 0.10 M20 40 44 0.09 0.04 0.97 Tri-Layer M21 68 720.10 0.47 6.40

As set forth in Table 10, the present invention made membranes which hadexcellent low areal resistance and/or low crossover. By taking intoaccount the properties provided by the present invention, one can obtaina balance of properties with respect to thickness, areal resistance, andmethanol crossover. When many of the embodiments of the presentinvention are compared to various membranes formed from commerciallyavailable Nafion®, one can see that the methanol crossover was quitelower for many embodiments of the present invention compared to themembranes formed from Nafion® and provided comparable areal resistance.This is all the more impressive considering that the embodiments of thepresent invention are generally non-perfluoronated polymers.

Other embodiments of the present invention will be apparent to thoseskilled in the art from consideration of the present specification andpractice of the present invention disclosed herein. It is intended thatthe present specification and examples be considered as exemplary onlywith a true scope and spirit of the invention being indicated by thefollowing claims and equivalents thereof.

1. A polyelectrolyte comprising: a) at least one acrylic and/or vinylresin or both having at least one ionic or ionizable group; and b) atleast one additional polymer, wherein a) and b) are different, whereina) has domain sizes of about 500 nm or less.
 2. The polyelectrolyte ofclaim 1, wherein said domain sizes are about 100 nm or less.
 3. Thepolyelectrolyte of claim 1, wherein said at least one additional polymeris a fluoropolymer.
 4. The polyelectrolyte of claim 1, wherein saidpolyelectrolyte, when formed into a film, has a conductivity of 20 mS/cmor greater.
 5. A composition comprising the polymer product of blending:a) at least one polymer comprising acrylic units, vinyl units or both,and at least one ionic or ionizable group; and b) at least onethermoplastic fluoropolymer, wherein a) and b) are different, wherein a)has domain sizes of about 500 nm or less.
 6. A polyelectrdlytecomprising: a) at least one acrylic and/or vinyl resin or both having atleast one ionic or ionizable group; and b) at least one additionalpolymer, wherein a) and b) are different, wherein said polyelectrolyte,when formed into a film, has a conductivity of about 20 mS/cm orgreater.
 7. The polyelectrolyte of claim 6, wherein said conductivity isfrom about 50 mS/cm to about 300 mS/cm.
 8. The polyelectrolyte of claim6, wherein said conductivity is from about 90 mS/cm to about 175 mS/cm.9. The polyelectrolyte of claim 6, wherein said additional polymer is afluorinated polymer.
 10. A polyelectrolyte comprising: a) at least oneacrylic and/or vinyl resin or both having at least one ionic orionizable group with at least one ammonium counterion and/or phosphoniumcounterion; and b) at least one additional polymer, wherein a) and b)are different.
 11. The polyelectrolyte of claim 10, wherein saidcounterion is a tetraalkyl ammonium counterion, a tetraaryl ammoniumcounterion, a tetraaralkyl ammonium counterion, or a cycloalkyl ammoniumcounterion, or phosphonium analogs thereof, or combinations thereof. 12.The polyelectrolyte of claim 10, wherein said ammonium counterioncomprises the formula NR₁R₂R₃R₄ ⁺, wherein R₁-R₄ are organic groups,which are independently selected from C₁₋₃₀ alkyl, aryl, aralkyl orcycloalkyl groups.
 13. The polyelectrolyte of claim 10, wherein saidammonium counterion is tetramethylammmonium, tetraethylammonium,tetrapropylammonium, tetrabutylammonium, tetrapentylammonium,tetrahexylammonium, benzyltrimethylammonium, benzyltriethylammonium,hexamethonium, decamethonium, cetyltrimethylammonium,decyltrimethylammonium, dodecyltrimethylammonium, ormethyltributylammonium, or combinations thereof.
 14. The polyelectrolyteof claim 10, wherein said ammonium counterion has a molecular weight ofat least
 186. 15. The polyelectrolyte of claim 10, wherein said ammoniumcounterion is an alkyl ammonium counterion.
 16. The polyelectrolyte ofclaim 10, wherein said ammonium counterion is a C₁-C₆ ammoniumcounterion.
 17. The polyelectrolyte of claim 10, wherein said additionalpolymer is a fluoropolymer.
 18. A method of making a polyelectrolytecomprising blending: a) at least one polymer comprising acrylic units,vinyl units, or both and at least one ionic or ionizable group; and b)at least one additional polymer, where a) and b) are different, whereinan ammonium compound or phosphonium compound is added prior to, during,and/or after said blending to form an ammonium or phosphonium salt andthen removing the ammonium or phosphonium compound or salt versionthereof.
 19. The method of claim 18, wherein the step of removing saidammonium or phosphonium compound or salt version thereof comprisesintroducing an acid, alkali metal, alkaline earth metal hydroxide, anaqueous solution, or combinations thereof in said blend.
 20. The methodof claim 18, wherein said polyelectrolyte is formed into a film ormembrane prior to removing said ammonium or phosphonium compound or saltversion thereof.
 21. The method of claim 18, wherein said ammoniumcompound is added prior to said blending.
 22. The method of claim 18,further comprising adding at least one cross-linker and optionally acatalyst to said blend in order to crosslink said blend after removingsaid ammonium or phosphonium compound or salt version thereof.
 23. Themethod of claim 18, wherein said ammonium compound is a alkyl ammoniumcompound.
 24. The method of claim 18, wherein said ammonium compound isformed into a quaternary ammonium salt once introduced into the blend.25. The method of claim 18, wherein said ammonium compound or saltthereof comprises the formula NR₁R₂R₃R₄ ⁺, wherein R₁-R₄ areindependently selected from C₁₋₃₀ alkyl, aryl, aralkyl or cycloalkylgroups.
 26. A method of forming a polyelectrolyte comprising blending:a) at least one polymer comprising acrylic units, vinyl units, or bothand at least one ionic or ionizable group; and b) at least oneadditional polymer, where a) and b) are different, associating at leastone ammonium and/or phosphonium counterion to at least a portion of saidionic group or said ionizable group prior to, during, and/or after saidblending; and substantially removing said ammonium and/or phosphoniumcounterion.
 27. The method of claim 26, further comprising cross-linkingsaid blend.
 28. A polyelectrolyte membrane comprising thepolyelectrolyte of claim
 1. 29. A membrane electrode assembly comprisingthe polyelectrolyte membrane of claim
 28. 30. A fuel cell comprising themembrane electrode assembly of claim
 29. 31. A fuel cell comprisinganode and cathode compartments separated by a polyelectrolyte membraneof claim
 28. 32. The fuel cell of claim 31, wherein said fuel celloperates with a liquid hydrocarbon fuel.
 33. The fuel cell of claim 32,wherein said fuel cell operates with a methanol fuel.
 34. A batterycomprising anode and cathode compartments separated by a polyelectrolytemembrane of claim
 28. 35. A polyelectrolyte membrane comprising: a) atleast one acrylic and/or vinyl resin or both having at least one ionicor ionizable group; and b) at least one additional polymer, wherein a)and b) are different, wherein said at least one ionic or ionizable groupis present in an amount of from about 200 to about 2,500 EW, and whereinsaid membrane has a methanol crossover rate of 5 ×10⁻¹⁶ mol/cm²/s orlower.
 36. The polyelectrolyte membrane of claim 35, wherein saidmembrane has a conductivity of 20 mS/cm or greater.
 37. Thepolyelectrolyte membrane of claim 36, wherein said conductivity is fromabout 50 mS/cm to about 300 mS/cm.
 38. The polyelectrolyte membrane ofclaim 35, wherein the membrane has a thickness of from about 0.5 toabout 10 mils.
 39. The polyelectrolyte membrane of claim 35, wherein thepolyelectrolyte membrane is non-perfluoronated.
 40. The polyelectrolytemembrane of claim 35, wherein said at least one ionic or ioniziablegroup is a sulfonate, phosphonate, a sulfonated group, a phosponatedgroup, a sulfonyl group, or combinations thereof.
 41. Thepolyelectrolyte membrane of claim 35, wherein the acrylic resin or vinylresin has an equivalent weight of from about 200 to about 8,000 EW. 42.A polyelectrolyte membrane formed by a method comprising blending: a) atleast one polymer comprising acrylic units, vinyl units, or both and atleast one ionic or ionizable group; and b) at least one additionalpolymer, where a) and b) are different, wherein an ammonium compound orphosphonium compound is added prior to, during, and/or after saidblending to form an ammonium or phosphonium salt and then removing theammonium or phosphonium compound or salt version thereof, wherein saidmembrane has a methanol crossover rate of 5×10⁻¹⁶ mol/cm²/s or lower.43. The polyelectrolyte membrane of claim 42, wherein said counterion isa tetraalkyl ammonium counterion, a tetraaryl ammonium counterion, atetraaralkyl ammonium counterion, or a cycloalkyl ammonium counterion,or phosphonium analogs thereof, or combinations thereof.
 44. Thepolyelectrolyte membrane of claim 42, wherein said ammonium counterioncomprises the formula NR₁R₂R₃R₄ ⁺, wherein R₁-R₄ are organic groups,which are independently selected from C₁₋₃₀ alkyl, aryl, aralkyl orcycloalkyl groups.
 45. The polyelectrolyte membrane of claim 42, whereinsaid ammonium counterion is tetramethylammmonium, tetraethylammonium,tetrapropylammonium, tetrabutylammonium, tetrapentylammonium,tetrahexylammonium, benzyltrimethylammonium, benzyltriethylammonium,hexamethonium, decamethonium, cetyltrimethylammonium,decyltrimethylammonium, dodecyltrimethylammonium, ormethyltributylammonium, or combinations thereof.
 46. The polyelectrolytemembrane of claim 42, wherein said ammonium counterion has a molecularweight of at least
 186. 47. The polyelectrolyte membrane of claim 42,wherein said ammonium counterion is an alkyl ammonium counterion. 48.The polyelectrolyte membrane of claim 42, wherein said ammoniumcounterion is a C₁-C₆ ammonium counterion.
 49. The polyelectrolytemembrane of claim 42, wherein said additional polymer is afluoropolymer.
 50. The polyelectrolyte membrane of claim 42, whereinsaid ammonium compound is formed into a quaternary ammonium salt onceintroduced into the blend.
 51. A multi-layer polyelectrolyte membranecomprising two or more layers, wherein at least one of said layerscomprises: a) at least one acrylic and/or vinyl resin or both having atleast one ionic or ionizable group; and b) at least one additionalpolymer, wherein a) and b) are different, wherein said at least oneionic or ionizable group is present in an amount of from about 200 toabout 2,500 EW, and wherein said membrane has a methanol crossover rateof 5 ×10⁻¹⁶ mol/cm2/s or lower.
 52. The multi-layer polyelectrolytemembrane of claim 51, wherein at least one other layer comprises: a) atleast one acrylic and/or vinyl resin or both having at least one ionicor ionizable group; and b) at least one additional polymer, wherein a)and b) are different, wherein said at least one ionic or ionizable groupis present in an amount of from about 200 to about 2,500 EW and whereinsaid other layer has the same or different composition as the firstlayer.
 53. The multi-layer membrane of claim 52, wherein the thicknessof each layer is the same.
 54. The multi-layer membrane of claim 52,wherein the thickness of each layer is different.
 55. A membraneelectrode assembly comprising the polyelectrolyte membrane of claim 35.56. A fuel cell comprising the membrane electrode assembly of claim 55.57. A fuel cell comprising anode and cathode compartments separated bythe polyelectrolyte membrane of claim
 35. 58. The fuel cell of claim 57,wherein said fuel cell operates with a liquid hydrocarbon fuel.
 59. Thefuel cell of claim 57, wherein said fuel cell operates with a methanolfuel.
 60. A battery comprising anode and cathode compartments separatedby the polyelectrolyte membrane of claim
 35. 61. A polyelectrolytemembrane comprising: a) at least one acrylic and/or vinyl resin or bothhaving at least one ionic or ionizable group; and b) at least oneadditional polymer, wherein a) and b) are different, wherein said atleast one ionic or ionizable group is present in an amount of from about200 to about 2,500 EW, and wherein said membrane has an areal resistanceof 0.3 Ω/cm² or lower.
 62. The membrane of claim 61, wherein saidmembrane has a methanol crossover rate of 5×10⁻¹⁶ mol/cm²/s or lower.63. The membrane of claim 61, wherein said membrane has a methanolcrossover rate of 3 ×10⁻¹⁶ mol/cm²/s or lower.
 64. The membrane of claim61, wherein said membrane has a methanol crossover rate of 1×10⁻¹⁶mol/cm²/s or lower.
 65. The membrane of claim 61, wherein said membranehas a methanol crossover rate of from 0.1×10⁻⁶ to 3×10⁻⁶ mol/cm²/s. 66.The membrane of claim 61, wherein said membrane has an areal resistanceof 0.1 Ω/cm² or lower.
 67. The membrane of claim 61, wherein saidmembrane has an areal resistance of from 0.05 to about 0.3 Ω/cm².
 68. Amulti-layer polyelectrolyte membrane comprising two or more layers,wherein at least one of said layers comprises: a) at least one acrylicand/or vinyl resin or both having at least one ionic or ionizable group;and b) at least one additional polymer, wherein a) and b) are different,wherein said at least one ionic or ionizable group is present in anamount of from about 200 to about 2,500 EW, and wherein said membranehas an areal resistance of 0.3 Ω/cm² or lower.
 69. The multi-layerpolyelectrolyte membrane of claim 68, wherein at least one other layercomprises: a) at least one acrylic and/or vinyl resin or both having atleast one ionic or ionizable group; and b) at least one additionalpolymer, wherein a) and b) are different, wherein said at least oneionic or ionizable group is present in an amount of from about 200 toabout 2,500 EW, and wherein said other layer has the same or differentcomposition as the first layer.
 70. The multi-layer membrane of claim69, wherein the thickness of each layer is the same.
 71. The multi-layermembrane of claim 69, wherein the thickness of each layer is different.72. A membrane electrode assembly comprising the polyelectrolytemembrane of claim
 68. 73. A fuel cell comprising the membrane electrodeassembly of claim
 72. 74. A fuel cell comprising anode and cathodecompartments separated by the polyelectrolyte membrane of claim
 68. 75.The fuel cell of claim 74, wherein said fuel cell operates with a liquidhydrocarbon fuel.
 76. The fuel cell of claim 74, wherein said fuel celloperates with a methanol fuel.
 77. A battery comprising anode andcathode compartments separated by the polyelectrolyte membrane of claim68.
 78. A membrane electrode assembly comprising the polyelectrolytemembrane of claim
 42. 79. A fuel cell comprising the membrane electrodeassembly of claim
 78. 80. A fuel cell comprising anode and cathodecompartments separated by the polyelectrolyte membrane of claim
 42. 81.The fuel cell of claim 80, wherein said fuel cell operates with a liquidhydrocarbon fuel.
 82. The fuel cell of claim 80, wherein said fuel celloperates with a methanol fuel.
 83. A battery comprising anode andcathode compartments separated by the polyelectrolyte membrane of claim42.
 84. A membrane electrode assembly comprising the polyelectrolytemembrane of claim
 61. 85. A fuel cell comprising the membrane electrodeof claim
 84. 86. A fuel cell comprising anode and cathode compartmentsseparated by the polyelectrolyte membrane of claim 68.